cc/layers/picture_layer

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This source file includes following definitions.
layer_needs_to_register_itself_
LayerTypeAsString
CreateLayerImpl
PushPropertiesTo
AppendQuads
DidUnregisterLayer
UpdateTilePriorities
DidBecomeActive
DidBeginTracing
ReleaseResources
CalculateContentsScale
GetPicture
SetHasGpuRasterizationHint
ShouldUseGpuRasterization
CreateTile
UpdatePile
GetInvalidation
GetTwinTiling
GetMaxTilesForInterestArea
GetSkewportTargetTimeInSeconds
GetSkewportExtrapolationLimitInContentPixels
CalculateTileSize
SyncFromActiveLayer
SyncTiling
SetIsMask
ContentsResourceId
MarkVisibleResourcesAsRequired
MarkVisibleTilesAsRequired
DoPostCommitInitialization
AddTiling
RemoveTiling
RemoveAllTilings
PositiveRatio
ManageTilings
ShouldAdjustRasterScale
SnappedContentsScale
RecalculateRasterScales
CleanUpTilingsOnActiveLayer
MinimumContentsScale
UpdateLCDTextStatus
ResetRasterScale
CanHaveTilings
CanHaveTilingWithScale
SanityCheckTilingState
GetDebugBorderProperties
AsValueInto
GPUMemoryUsageInBytes
RunMicroBenchmark
GetTree
IsOnActiveOrPendingTree
current_stage_
// Copyright 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "cc/layers/picture_layer_impl.h"

#include <algorithm>
#include <limits>

#include "base/time/time.h"
#include "cc/base/math_util.h"
#include "cc/base/util.h"
#include "cc/debug/debug_colors.h"
#include "cc/debug/micro_benchmark_impl.h"
#include "cc/debug/traced_value.h"
#include "cc/layers/append_quads_data.h"
#include "cc/layers/quad_sink.h"
#include "cc/quads/checkerboard_draw_quad.h"
#include "cc/quads/debug_border_draw_quad.h"
#include "cc/quads/picture_draw_quad.h"
#include "cc/quads/solid_color_draw_quad.h"
#include "cc/quads/tile_draw_quad.h"
#include "cc/resources/tile_manager.h"
#include "cc/trees/layer_tree_impl.h"
#include "ui/gfx/quad_f.h"
#include "ui/gfx/rect_conversions.h"
#include "ui/gfx/size_conversions.h"

namespace {
const float kMaxScaleRatioDuringPinch = 2.0f;

// When creating a new tiling during pinch, snap to an existing
// tiling's scale if the desired scale is within this ratio.
const float kSnapToExistingTilingRatio = 0.2f;
}

namespace cc {

PictureLayerImpl::PictureLayerImpl(LayerTreeImpl* tree_impl, int id)
    : LayerImpl(tree_impl, id),
      twin_layer_(NULL),
      pile_(PicturePileImpl::Create()),
      is_mask_(false),
      ideal_page_scale_(0.f),
      ideal_device_scale_(0.f),
      ideal_source_scale_(0.f),
      ideal_contents_scale_(0.f),
      raster_page_scale_(0.f),
      raster_device_scale_(0.f),
      raster_source_scale_(0.f),
      raster_contents_scale_(0.f),
      low_res_raster_contents_scale_(0.f),
      raster_source_scale_was_animating_(false),
      is_using_lcd_text_(tree_impl->settings().can_use_lcd_text),
      needs_post_commit_initialization_(true),
      should_update_tile_priorities_(false),
      has_gpu_rasterization_hint_(false),
      should_use_low_res_tiling_(tree_impl->settings().create_low_res_tiling),
      layer_needs_to_register_itself_(true) {}

PictureLayerImpl::~PictureLayerImpl() {
  if (!layer_needs_to_register_itself_)
    layer_tree_impl()->tile_manager()->UnregisterPictureLayerImpl(this);
}

const char* PictureLayerImpl::LayerTypeAsString() const {
  return "cc::PictureLayerImpl";
}

scoped_ptr<LayerImpl> PictureLayerImpl::CreateLayerImpl(
    LayerTreeImpl* tree_impl) {
  return PictureLayerImpl::Create(tree_impl, id()).PassAs<LayerImpl>();
}

void PictureLayerImpl::PushPropertiesTo(LayerImpl* base_layer) {
  // It's possible this layer was never drawn or updated (e.g. because it was
  // a descendant of an opacity 0 layer).
  DoPostCommitInitializationIfNeeded();
  PictureLayerImpl* layer_impl = static_cast<PictureLayerImpl*>(base_layer);

  // We have already synced the important bits from the the active layer, and
  // we will soon swap out its tilings and use them for recycling. However,
  // there are now tiles in this layer's tilings that were unref'd and replaced
  // with new tiles (due to invalidation). This resets all active priorities on
  // the to-be-recycled tiling to ensure replaced tiles don't linger and take
  // memory (due to a stale 'active' priority).
  if (layer_impl->tilings_)
    layer_impl->tilings_->DidBecomeRecycled();

  LayerImpl::PushPropertiesTo(base_layer);

  // When the pending tree pushes to the active tree, the pending twin
  // disappears.
  layer_impl->twin_layer_ = NULL;
  twin_layer_ = NULL;

  layer_impl->SetIsMask(is_mask_);
  layer_impl->pile_ = pile_;
  layer_impl->SetHasGpuRasterizationHint(has_gpu_rasterization_hint_);

  // Tilings would be expensive to push, so we swap.  This optimization requires
  // an extra invalidation in SyncFromActiveLayer.
  layer_impl->tilings_.swap(tilings_);
  layer_impl->tilings_->SetClient(layer_impl);
  if (tilings_)
    tilings_->SetClient(this);

  layer_impl->raster_page_scale_ = raster_page_scale_;
  layer_impl->raster_device_scale_ = raster_device_scale_;
  layer_impl->raster_source_scale_ = raster_source_scale_;
  layer_impl->raster_contents_scale_ = raster_contents_scale_;
  layer_impl->low_res_raster_contents_scale_ = low_res_raster_contents_scale_;

  layer_impl->UpdateLCDTextStatus(is_using_lcd_text_);
  layer_impl->needs_post_commit_initialization_ = false;

  // The invalidation on this soon-to-be-recycled layer must be cleared to
  // mirror clearing the invalidation in PictureLayer's version of this function
  // in case push properties is skipped.
  layer_impl->invalidation_.Swap(&invalidation_);
  invalidation_.Clear();
  needs_post_commit_initialization_ = true;

  // We always need to push properties.
  // See http://crbug.com/303943
  needs_push_properties_ = true;
}

void PictureLayerImpl::AppendQuads(QuadSink* quad_sink,
                                   AppendQuadsData* append_quads_data) {
  DCHECK(!needs_post_commit_initialization_);
  gfx::Rect rect(visible_content_rect());
  gfx::Rect content_rect(content_bounds());

  SharedQuadState* shared_quad_state =
      quad_sink->UseSharedQuadState(CreateSharedQuadState());

  if (current_draw_mode_ == DRAW_MODE_RESOURCELESS_SOFTWARE) {
    AppendDebugBorderQuad(
        quad_sink,
        shared_quad_state,
        append_quads_data,
        DebugColors::DirectPictureBorderColor(),
        DebugColors::DirectPictureBorderWidth(layer_tree_impl()));

    gfx::Rect geometry_rect = rect;
    gfx::Rect opaque_rect = contents_opaque() ? geometry_rect : gfx::Rect();
    gfx::Rect visible_geometry_rect = geometry_rect;
    gfx::Size texture_size = rect.size();
    gfx::RectF texture_rect = gfx::RectF(texture_size);
    gfx::Rect quad_content_rect = rect;
    float contents_scale = contents_scale_x();

    scoped_ptr<PictureDrawQuad> quad = PictureDrawQuad::Create();
    quad->SetNew(shared_quad_state,
                 geometry_rect,
                 opaque_rect,
                 visible_geometry_rect,
                 texture_rect,
                 texture_size,
                 RGBA_8888,
                 quad_content_rect,
                 contents_scale,
                 pile_);
    if (quad_sink->MaybeAppend(quad.PassAs<DrawQuad>()))
      append_quads_data->num_missing_tiles++;
    return;
  }

  AppendDebugBorderQuad(quad_sink, shared_quad_state, append_quads_data);

  if (ShowDebugBorders()) {
    for (PictureLayerTilingSet::CoverageIterator iter(
        tilings_.get(), contents_scale_x(), rect, ideal_contents_scale_);
         iter;
         ++iter) {
      SkColor color;
      float width;
      if (*iter && iter->IsReadyToDraw()) {
        ManagedTileState::TileVersion::Mode mode =
            iter->GetTileVersionForDrawing().mode();
        if (mode == ManagedTileState::TileVersion::SOLID_COLOR_MODE) {
          color = DebugColors::SolidColorTileBorderColor();
          width = DebugColors::SolidColorTileBorderWidth(layer_tree_impl());
        } else if (mode == ManagedTileState::TileVersion::PICTURE_PILE_MODE) {
          color = DebugColors::PictureTileBorderColor();
          width = DebugColors::PictureTileBorderWidth(layer_tree_impl());
        } else if (iter->priority(ACTIVE_TREE).resolution == HIGH_RESOLUTION) {
          color = DebugColors::HighResTileBorderColor();
          width = DebugColors::HighResTileBorderWidth(layer_tree_impl());
        } else if (iter->priority(ACTIVE_TREE).resolution == LOW_RESOLUTION) {
          color = DebugColors::LowResTileBorderColor();
          width = DebugColors::LowResTileBorderWidth(layer_tree_impl());
        } else if (iter->contents_scale() > contents_scale_x()) {
          color = DebugColors::ExtraHighResTileBorderColor();
          width = DebugColors::ExtraHighResTileBorderWidth(layer_tree_impl());
        } else {
          color = DebugColors::ExtraLowResTileBorderColor();
          width = DebugColors::ExtraLowResTileBorderWidth(layer_tree_impl());
        }
      } else {
        color = DebugColors::MissingTileBorderColor();
        width = DebugColors::MissingTileBorderWidth(layer_tree_impl());
      }

      scoped_ptr<DebugBorderDrawQuad> debug_border_quad =
          DebugBorderDrawQuad::Create();
      gfx::Rect geometry_rect = iter.geometry_rect();
      gfx::Rect visible_geometry_rect = geometry_rect;
      debug_border_quad->SetNew(shared_quad_state,
                                geometry_rect,
                                visible_geometry_rect,
                                color,
                                width);
      quad_sink->MaybeAppend(debug_border_quad.PassAs<DrawQuad>());
    }
  }

  // Keep track of the tilings that were used so that tilings that are
  // unused can be considered for removal.
  std::vector<PictureLayerTiling*> seen_tilings;

  for (PictureLayerTilingSet::CoverageIterator iter(
      tilings_.get(), contents_scale_x(), rect, ideal_contents_scale_);
       iter;
       ++iter) {
    gfx::Rect geometry_rect = iter.geometry_rect();
    gfx::Rect visible_geometry_rect = geometry_rect;
    if (!*iter || !iter->IsReadyToDraw()) {
      if (draw_checkerboard_for_missing_tiles()) {
        // TODO(enne): Figure out how to show debug "invalidated checker" color
        scoped_ptr<CheckerboardDrawQuad> quad = CheckerboardDrawQuad::Create();
        SkColor color = DebugColors::DefaultCheckerboardColor();
        quad->SetNew(
            shared_quad_state, geometry_rect, visible_geometry_rect, color);
        if (quad_sink->MaybeAppend(quad.PassAs<DrawQuad>()))
          append_quads_data->num_missing_tiles++;
      } else {
        SkColor color = SafeOpaqueBackgroundColor();
        scoped_ptr<SolidColorDrawQuad> quad = SolidColorDrawQuad::Create();
        quad->SetNew(shared_quad_state,
                     geometry_rect,
                     visible_geometry_rect,
                     color,
                     false);
        if (quad_sink->MaybeAppend(quad.PassAs<DrawQuad>()))
          append_quads_data->num_missing_tiles++;
      }

      append_quads_data->had_incomplete_tile = true;
      continue;
    }

    const ManagedTileState::TileVersion& tile_version =
        iter->GetTileVersionForDrawing();
    scoped_ptr<DrawQuad> draw_quad;
    switch (tile_version.mode()) {
      case ManagedTileState::TileVersion::RESOURCE_MODE: {
        gfx::RectF texture_rect = iter.texture_rect();
        gfx::Rect opaque_rect = iter->opaque_rect();
        opaque_rect.Intersect(geometry_rect);

        if (iter->contents_scale() != ideal_contents_scale_)
          append_quads_data->had_incomplete_tile = true;

        scoped_ptr<TileDrawQuad> quad = TileDrawQuad::Create();
        quad->SetNew(shared_quad_state,
                     geometry_rect,
                     opaque_rect,
                     visible_geometry_rect,
                     tile_version.get_resource_id(),
                     texture_rect,
                     iter.texture_size(),
                     tile_version.contents_swizzled());
        draw_quad = quad.PassAs<DrawQuad>();
        break;
      }
      case ManagedTileState::TileVersion::PICTURE_PILE_MODE: {
        gfx::RectF texture_rect = iter.texture_rect();
        gfx::Rect opaque_rect = iter->opaque_rect();
        opaque_rect.Intersect(geometry_rect);

        ResourceProvider* resource_provider =
            layer_tree_impl()->resource_provider();
        ResourceFormat format =
            resource_provider->memory_efficient_texture_format();
        scoped_ptr<PictureDrawQuad> quad = PictureDrawQuad::Create();
        quad->SetNew(shared_quad_state,
                     geometry_rect,
                     opaque_rect,
                     visible_geometry_rect,
                     texture_rect,
                     iter.texture_size(),
                     format,
                     iter->content_rect(),
                     iter->contents_scale(),
                     pile_);
        draw_quad = quad.PassAs<DrawQuad>();
        break;
      }
      case ManagedTileState::TileVersion::SOLID_COLOR_MODE: {
        scoped_ptr<SolidColorDrawQuad> quad = SolidColorDrawQuad::Create();
        quad->SetNew(shared_quad_state,
                     geometry_rect,
                     visible_geometry_rect,
                     tile_version.get_solid_color(),
                     false);
        draw_quad = quad.PassAs<DrawQuad>();
        break;
      }
    }

    DCHECK(draw_quad);
    quad_sink->MaybeAppend(draw_quad.Pass());

    if (seen_tilings.empty() || seen_tilings.back() != iter.CurrentTiling())
      seen_tilings.push_back(iter.CurrentTiling());
  }

  // Aggressively remove any tilings that are not seen to save memory. Note
  // that this is at the expense of doing cause more frequent re-painting. A
  // better scheme would be to maintain a tighter visible_content_rect for the
  // finer tilings.
  CleanUpTilingsOnActiveLayer(seen_tilings);
}

void PictureLayerImpl::DidUnregisterLayer() {
  layer_needs_to_register_itself_ = true;
}

void PictureLayerImpl::UpdateTilePriorities() {
  DCHECK(!needs_post_commit_initialization_);
  CHECK(should_update_tile_priorities_);

  if (layer_needs_to_register_itself_) {
    layer_tree_impl()->tile_manager()->RegisterPictureLayerImpl(this);
    layer_needs_to_register_itself_ = false;
  }

  if (!layer_tree_impl()->device_viewport_valid_for_tile_management()) {
    for (size_t i = 0; i < tilings_->num_tilings(); ++i)
      DCHECK(tilings_->tiling_at(i)->has_ever_been_updated());
    return;
  }

  if (!tilings_->num_tilings())
    return;

  double current_frame_time_in_seconds =
      (layer_tree_impl()->CurrentFrameTimeTicks() -
       base::TimeTicks()).InSecondsF();

  bool tiling_needs_update = false;
  for (size_t i = 0; i < tilings_->num_tilings(); ++i) {
    if (tilings_->tiling_at(i)->NeedsUpdateForFrameAtTime(
            current_frame_time_in_seconds)) {
      tiling_needs_update = true;
      break;
    }
  }
  if (!tiling_needs_update)
    return;

  UpdateLCDTextStatus(can_use_lcd_text());

  // Use visible_content_rect, unless it's empty. If it's empty, then
  // try to inverse project the viewport into layer space and use that.
  gfx::Rect visible_rect_in_content_space = visible_content_rect();
  if (visible_rect_in_content_space.IsEmpty()) {
    gfx::Transform screen_to_layer(gfx::Transform::kSkipInitialization);
    if (screen_space_transform().GetInverse(&screen_to_layer)) {
      gfx::Size viewport_size = layer_tree_impl()->DrawViewportSize();
      visible_rect_in_content_space =
          gfx::ToEnclosingRect(MathUtil::ProjectClippedRect(
              screen_to_layer, gfx::Rect(viewport_size)));
      visible_rect_in_content_space.Intersect(gfx::Rect(content_bounds()));
    }
  }

  WhichTree tree =
      layer_tree_impl()->IsActiveTree() ? ACTIVE_TREE : PENDING_TREE;

  tilings_->UpdateTilePriorities(tree,
                                 visible_rect_in_content_space,
                                 contents_scale_x(),
                                 current_frame_time_in_seconds);

  if (layer_tree_impl()->IsPendingTree())
    MarkVisibleResourcesAsRequired();

  // Tile priorities were modified.
  layer_tree_impl()->DidModifyTilePriorities();
}

void PictureLayerImpl::DidBecomeActive() {
  LayerImpl::DidBecomeActive();
  tilings_->DidBecomeActive();
  layer_tree_impl()->DidModifyTilePriorities();
}

void PictureLayerImpl::DidBeginTracing() {
  pile_->DidBeginTracing();
}

void PictureLayerImpl::ReleaseResources() {
  if (tilings_)
    RemoveAllTilings();

  ResetRasterScale();
}

void PictureLayerImpl::CalculateContentsScale(
    float ideal_contents_scale,
    float device_scale_factor,
    float page_scale_factor,
    bool animating_transform_to_screen,
    float* contents_scale_x,
    float* contents_scale_y,
    gfx::Size* content_bounds) {
  DoPostCommitInitializationIfNeeded();

  // This function sets valid raster scales and manages tilings, so tile
  // priorities can now be updated.
  should_update_tile_priorities_ = true;

  if (!CanHaveTilings()) {
    ideal_page_scale_ = page_scale_factor;
    ideal_device_scale_ = device_scale_factor;
    ideal_contents_scale_ = ideal_contents_scale;
    ideal_source_scale_ =
        ideal_contents_scale_ / ideal_page_scale_ / ideal_device_scale_;
    *contents_scale_x = ideal_contents_scale_;
    *contents_scale_y = ideal_contents_scale_;
    *content_bounds = gfx::ToCeiledSize(gfx::ScaleSize(bounds(),
                                                       ideal_contents_scale_,
                                                       ideal_contents_scale_));
    return;
  }

  float min_contents_scale = MinimumContentsScale();
  DCHECK_GT(min_contents_scale, 0.f);
  float min_page_scale = layer_tree_impl()->min_page_scale_factor();
  DCHECK_GT(min_page_scale, 0.f);
  float min_device_scale = 1.f;
  float min_source_scale =
      min_contents_scale / min_page_scale / min_device_scale;

  float ideal_page_scale = page_scale_factor;
  float ideal_device_scale = device_scale_factor;
  float ideal_source_scale =
      ideal_contents_scale / ideal_page_scale / ideal_device_scale;

  ideal_contents_scale_ = std::max(ideal_contents_scale, min_contents_scale);
  ideal_page_scale_ = ideal_page_scale;
  ideal_device_scale_ = ideal_device_scale;
  ideal_source_scale_ = std::max(ideal_source_scale, min_source_scale);

  ManageTilings(animating_transform_to_screen);

  // The content scale and bounds for a PictureLayerImpl is somewhat fictitious.
  // There are (usually) several tilings at different scales.  However, the
  // content bounds is the (integer!) space in which quads are generated.
  // In order to guarantee that we can fill this integer space with any set of
  // tilings (and then map back to floating point texture coordinates), the
  // contents scale must be at least as large as the largest of the tilings.
  float max_contents_scale = min_contents_scale;
  for (size_t i = 0; i < tilings_->num_tilings(); ++i) {
    const PictureLayerTiling* tiling = tilings_->tiling_at(i);
    max_contents_scale = std::max(max_contents_scale, tiling->contents_scale());
  }

  *contents_scale_x = max_contents_scale;
  *contents_scale_y = max_contents_scale;
  *content_bounds = gfx::ToCeiledSize(
      gfx::ScaleSize(bounds(), max_contents_scale, max_contents_scale));
}

skia::RefPtr<SkPicture> PictureLayerImpl::GetPicture() {
  return pile_->GetFlattenedPicture();
}

void PictureLayerImpl::SetHasGpuRasterizationHint(bool has_hint) {
  bool old_should_use_gpu_rasterization = ShouldUseGpuRasterization();
  has_gpu_rasterization_hint_ = has_hint;
  if (ShouldUseGpuRasterization() != old_should_use_gpu_rasterization)
    RemoveAllTilings();
}

bool PictureLayerImpl::ShouldUseGpuRasterization() const {
  switch (layer_tree_impl()->settings().rasterization_site) {
    case LayerTreeSettings::CpuRasterization:
      return false;
    case LayerTreeSettings::HybridRasterization:
      return has_gpu_rasterization_hint_;
    case LayerTreeSettings::GpuRasterization:
      return true;
  }
  NOTREACHED();
  return false;
}

scoped_refptr<Tile> PictureLayerImpl::CreateTile(PictureLayerTiling* tiling,
                                               const gfx::Rect& content_rect) {
  if (!pile_->CanRaster(tiling->contents_scale(), content_rect))
    return scoped_refptr<Tile>();

  int flags = 0;
  if (is_using_lcd_text_)
    flags |= Tile::USE_LCD_TEXT;
  if (ShouldUseGpuRasterization())
    flags |= Tile::USE_GPU_RASTERIZATION;
  return layer_tree_impl()->tile_manager()->CreateTile(
      pile_.get(),
      content_rect.size(),
      content_rect,
      contents_opaque() ? content_rect : gfx::Rect(),
      tiling->contents_scale(),
      id(),
      layer_tree_impl()->source_frame_number(),
      flags);
}

void PictureLayerImpl::UpdatePile(Tile* tile) {
  tile->set_picture_pile(pile_);
}

const Region* PictureLayerImpl::GetInvalidation() {
  return &invalidation_;
}

const PictureLayerTiling* PictureLayerImpl::GetTwinTiling(
    const PictureLayerTiling* tiling) const {

  if (!twin_layer_ ||
      twin_layer_->ShouldUseGpuRasterization() != ShouldUseGpuRasterization())
    return NULL;
  for (size_t i = 0; i < twin_layer_->tilings_->num_tilings(); ++i)
    if (twin_layer_->tilings_->tiling_at(i)->contents_scale() ==
        tiling->contents_scale())
      return twin_layer_->tilings_->tiling_at(i);
  return NULL;
}

size_t PictureLayerImpl::GetMaxTilesForInterestArea() const {
  return layer_tree_impl()->settings().max_tiles_for_interest_area;
}

float PictureLayerImpl::GetSkewportTargetTimeInSeconds() const {
  return layer_tree_impl()->settings().skewport_target_time_in_seconds;
}

int PictureLayerImpl::GetSkewportExtrapolationLimitInContentPixels() const {
  return layer_tree_impl()
      ->settings()
      .skewport_extrapolation_limit_in_content_pixels;
}

gfx::Size PictureLayerImpl::CalculateTileSize(
    const gfx::Size& content_bounds) const {
  if (is_mask_) {
    int max_size = layer_tree_impl()->MaxTextureSize();
    return gfx::Size(
        std::min(max_size, content_bounds.width()),
        std::min(max_size, content_bounds.height()));
  }

  int max_texture_size =
      layer_tree_impl()->resource_provider()->max_texture_size();

  gfx::Size default_tile_size = layer_tree_impl()->settings().default_tile_size;
  default_tile_size.SetToMin(gfx::Size(max_texture_size, max_texture_size));

  gfx::Size max_untiled_content_size =
      layer_tree_impl()->settings().max_untiled_layer_size;
  max_untiled_content_size.SetToMin(
      gfx::Size(max_texture_size, max_texture_size));

  bool any_dimension_too_large =
      content_bounds.width() > max_untiled_content_size.width() ||
      content_bounds.height() > max_untiled_content_size.height();

  bool any_dimension_one_tile =
      content_bounds.width() <= default_tile_size.width() ||
      content_bounds.height() <= default_tile_size.height();

  // If long and skinny, tile at the max untiled content size, and clamp
  // the smaller dimension to the content size, e.g. 1000x12 layer with
  // 500x500 max untiled size would get 500x12 tiles.  Also do this
  // if the layer is small.
  if (any_dimension_one_tile || !any_dimension_too_large) {
    int width =
        std::min(max_untiled_content_size.width(), content_bounds.width());
    int height =
        std::min(max_untiled_content_size.height(), content_bounds.height());
    // Round width and height up to the closest multiple of 64, or 56 if
    // we should avoid power-of-two textures. This helps reduce the number
    // of different textures sizes to help recycling, and also keeps all
    // textures multiple-of-eight, which is preferred on some drivers (IMG).
    bool avoid_pow2 =
        layer_tree_impl()->GetRendererCapabilities().avoid_pow2_textures;
    int round_up_to = avoid_pow2 ? 56 : 64;
    width = RoundUp(width, round_up_to);
    height = RoundUp(height, round_up_to);
    return gfx::Size(width, height);
  }

  return default_tile_size;
}

void PictureLayerImpl::SyncFromActiveLayer(const PictureLayerImpl* other) {
  DCHECK(!other->needs_post_commit_initialization_);
  DCHECK(other->tilings_);

  UpdateLCDTextStatus(other->is_using_lcd_text_);

  if (!DrawsContent()) {
    RemoveAllTilings();
    return;
  }

  raster_page_scale_ = other->raster_page_scale_;
  raster_device_scale_ = other->raster_device_scale_;
  raster_source_scale_ = other->raster_source_scale_;
  raster_contents_scale_ = other->raster_contents_scale_;
  low_res_raster_contents_scale_ = other->low_res_raster_contents_scale_;

  // Add synthetic invalidations for any recordings that were dropped.  As
  // tiles are updated to point to this new pile, this will force the dropping
  // of tiles that can no longer be rastered.  This is not ideal, but is a
  // trade-off for memory (use the same pile as much as possible, by switching
  // during DidBecomeActive) and for time (don't bother checking every tile
  // during activation to see if the new pile can still raster it).
  for (int x = 0; x < pile_->num_tiles_x(); ++x) {
    for (int y = 0; y < pile_->num_tiles_y(); ++y) {
      bool previously_had = other->pile_->HasRecordingAt(x, y);
      bool now_has = pile_->HasRecordingAt(x, y);
      if (now_has || !previously_had)
        continue;
      gfx::Rect layer_rect = pile_->tile_bounds(x, y);
      invalidation_.Union(layer_rect);
    }
  }

  // Union in the other newly exposed regions as invalid.
  Region difference_region = Region(gfx::Rect(bounds()));
  difference_region.Subtract(gfx::Rect(other->bounds()));
  invalidation_.Union(difference_region);

  if (CanHaveTilings()) {
    // The recycle tree's tiling set is two frames out of date, so it needs to
    // have both this frame's invalidation and the previous frame's invalidation
    // (stored on the active layer).
    Region tiling_invalidation = other->invalidation_;
    tiling_invalidation.Union(invalidation_);
    tilings_->SyncTilings(*other->tilings_,
                          bounds(),
                          tiling_invalidation,
                          MinimumContentsScale());
  } else {
    RemoveAllTilings();
  }

  SanityCheckTilingState();
}

void PictureLayerImpl::SyncTiling(
    const PictureLayerTiling* tiling) {
  if (!CanHaveTilingWithScale(tiling->contents_scale()))
    return;
  tilings_->AddTiling(tiling->contents_scale());

  // If this tree needs update draw properties, then the tiling will
  // get updated prior to drawing or activation.  If this tree does not
  // need update draw properties, then its transforms are up to date and
  // we can create tiles for this tiling immediately.
  if (!layer_tree_impl()->needs_update_draw_properties() &&
      should_update_tile_priorities_)
    UpdateTilePriorities();
}

void PictureLayerImpl::SetIsMask(bool is_mask) {
  if (is_mask_ == is_mask)
    return;
  is_mask_ = is_mask;
  if (tilings_)
    tilings_->RemoveAllTiles();
}

ResourceProvider::ResourceId PictureLayerImpl::ContentsResourceId() const {
  gfx::Rect content_rect(content_bounds());
  float scale = contents_scale_x();
  PictureLayerTilingSet::CoverageIterator iter(
      tilings_.get(), scale, content_rect, ideal_contents_scale_);

  // Mask resource not ready yet.
  if (!iter || !*iter)
    return 0;

  // Masks only supported if they fit on exactly one tile.
  if (iter.geometry_rect() != content_rect)
    return 0;

  const ManagedTileState::TileVersion& tile_version =
      iter->GetTileVersionForDrawing();
  if (!tile_version.IsReadyToDraw() ||
      tile_version.mode() != ManagedTileState::TileVersion::RESOURCE_MODE)
    return 0;

  return tile_version.get_resource_id();
}

void PictureLayerImpl::MarkVisibleResourcesAsRequired() const {
  DCHECK(layer_tree_impl()->IsPendingTree());
  DCHECK(!layer_tree_impl()->needs_update_draw_properties());
  DCHECK(ideal_contents_scale_);
  DCHECK_GT(tilings_->num_tilings(), 0u);

  // The goal of this function is to find the minimum set of tiles that need to
  // be ready to draw in order to activate without flashing content from a
  // higher res on the active tree to a lower res on the pending tree.

  gfx::Rect rect(visible_content_rect());

  float min_acceptable_scale =
      std::min(raster_contents_scale_, ideal_contents_scale_);

  if (PictureLayerImpl* twin = twin_layer_) {
    float twin_min_acceptable_scale =
        std::min(twin->ideal_contents_scale_, twin->raster_contents_scale_);
    // Ignore 0 scale in case CalculateContentsScale() has never been
    // called for active twin.
    if (twin_min_acceptable_scale != 0.0f) {
      min_acceptable_scale =
          std::min(min_acceptable_scale, twin_min_acceptable_scale);
    }
  }

  PictureLayerTiling* high_res = NULL;
  PictureLayerTiling* low_res = NULL;

  // First pass: ready to draw tiles in acceptable but non-ideal tilings are
  // marked as required for activation so that their textures are not thrown
  // away; any non-ready tiles are not marked as required.
  Region missing_region = rect;
  for (size_t i = 0; i < tilings_->num_tilings(); ++i) {
    PictureLayerTiling* tiling = tilings_->tiling_at(i);
    DCHECK(tiling->has_ever_been_updated());

    if (tiling->resolution() == LOW_RESOLUTION) {
      DCHECK(!low_res) << "There can only be one low res tiling";
      low_res = tiling;
    }
    if (tiling->contents_scale() < min_acceptable_scale)
      continue;
    if (tiling->resolution() == HIGH_RESOLUTION) {
      DCHECK(!high_res) << "There can only be one high res tiling";
      high_res = tiling;
      continue;
    }
    for (PictureLayerTiling::CoverageIterator iter(tiling,
                                                   contents_scale_x(),
                                                   rect);
         iter;
         ++iter) {
      if (!*iter || !iter->IsReadyToDraw())
        continue;

      missing_region.Subtract(iter.geometry_rect());
      iter->MarkRequiredForActivation();
    }
  }
  DCHECK(high_res) << "There must be one high res tiling";

  // If these pointers are null (because no twin, no matching tiling, or the
  // simpification just below), then high res tiles will be required to fill any
  // holes left by the first pass above.  If the pointers are valid, then this
  // layer is allowed to skip any tiles that are not ready on its twin.
  const PictureLayerTiling* twin_high_res = NULL;
  const PictureLayerTiling* twin_low_res = NULL;

  // As a simplification, only allow activating to skip twin tiles that the
  // active layer is also missing when both this layer and its twin have 2
  // tilings (high and low).  This avoids having to iterate/track coverage of
  // non-ideal tilings during the last draw call on the active layer.
  if (high_res && low_res && tilings_->num_tilings() == 2 &&
      twin_layer_ && twin_layer_->tilings_->num_tilings() == 2) {
    twin_low_res = GetTwinTiling(low_res);
    if (twin_low_res)
      twin_high_res = GetTwinTiling(high_res);
  }
  // If this layer and its twin have different transforms, then don't compare
  // them and only allow activating to high res tiles, since tiles on each layer
  // will be in different places on screen.
  if (!twin_high_res || !twin_low_res ||
      twin_layer_->layer_tree_impl()->RequiresHighResToDraw() ||
      draw_properties().screen_space_transform !=
          twin_layer_->draw_properties().screen_space_transform) {
    twin_high_res = NULL;
    twin_low_res = NULL;
  }

  // As a second pass, mark as required any visible high res tiles not filled in
  // by acceptable non-ideal tiles from the first pass.
  if (MarkVisibleTilesAsRequired(
      high_res, twin_high_res, contents_scale_x(), rect, missing_region)) {
    // As an optional third pass, if a high res tile was skipped because its
    // twin was also missing, then fall back to mark low res tiles as required
    // in case the active twin is substituting those for missing high res
    // content.
    MarkVisibleTilesAsRequired(
        low_res, twin_low_res, contents_scale_x(), rect, missing_region);
  }
}

bool PictureLayerImpl::MarkVisibleTilesAsRequired(
    PictureLayerTiling* tiling,
    const PictureLayerTiling* optional_twin_tiling,
    float contents_scale,
    const gfx::Rect& rect,
    const Region& missing_region) const {
  bool twin_had_missing_tile = false;
  for (PictureLayerTiling::CoverageIterator iter(tiling,
                                                 contents_scale,
                                                 rect);
       iter;
       ++iter) {
    Tile* tile = *iter;
    // A null tile (i.e. missing recording) can just be skipped.
    if (!tile)
      continue;

    // If the missing region doesn't cover it, this tile is fully
    // covered by acceptable tiles at other scales.
    if (!missing_region.Intersects(iter.geometry_rect()))
      continue;

    // If the twin tile doesn't exist (i.e. missing recording or so far away
    // that it is outside the visible tile rect) or this tile is shared between
    // with the twin, then this tile isn't required to prevent flashing.
    if (optional_twin_tiling) {
      Tile* twin_tile = optional_twin_tiling->TileAt(iter.i(), iter.j());
      if (!twin_tile || twin_tile == tile) {
        twin_had_missing_tile = true;
        continue;
      }
    }

    tile->MarkRequiredForActivation();
  }
  return twin_had_missing_tile;
}

void PictureLayerImpl::DoPostCommitInitialization() {
  DCHECK(needs_post_commit_initialization_);
  DCHECK(layer_tree_impl()->IsPendingTree());

  if (!tilings_)
    tilings_.reset(new PictureLayerTilingSet(this, bounds()));

  DCHECK(!twin_layer_);
  twin_layer_ = static_cast<PictureLayerImpl*>(
      layer_tree_impl()->FindActiveTreeLayerById(id()));
  if (twin_layer_) {
    DCHECK(!twin_layer_->twin_layer_);
    twin_layer_->twin_layer_ = this;
    // If the twin has never been pushed to, do not sync from it.
    // This can happen if this function is called during activation.
    if (!twin_layer_->needs_post_commit_initialization_)
      SyncFromActiveLayer(twin_layer_);
  }

  needs_post_commit_initialization_ = false;
}

PictureLayerTiling* PictureLayerImpl::AddTiling(float contents_scale) {
  DCHECK(CanHaveTilingWithScale(contents_scale)) <<
      "contents_scale: " << contents_scale;

  PictureLayerTiling* tiling = tilings_->AddTiling(contents_scale);

  DCHECK(pile_->HasRecordings());

  if (twin_layer_ &&
      twin_layer_->ShouldUseGpuRasterization() == ShouldUseGpuRasterization())
    twin_layer_->SyncTiling(tiling);

  return tiling;
}

void PictureLayerImpl::RemoveTiling(float contents_scale) {
  for (size_t i = 0; i < tilings_->num_tilings(); ++i) {
    PictureLayerTiling* tiling = tilings_->tiling_at(i);
    if (tiling->contents_scale() == contents_scale) {
      tilings_->Remove(tiling);
      break;
    }
  }
  if (tilings_->num_tilings() == 0)
    ResetRasterScale();
  SanityCheckTilingState();
}

void PictureLayerImpl::RemoveAllTilings() {
  if (tilings_)
    tilings_->RemoveAllTilings();
  // If there are no tilings, then raster scales are no longer meaningful.
  ResetRasterScale();
}

namespace {

inline float PositiveRatio(float float1, float float2) {
  DCHECK_GT(float1, 0);
  DCHECK_GT(float2, 0);
  return float1 > float2 ? float1 / float2 : float2 / float1;
}

}  // namespace

void PictureLayerImpl::ManageTilings(bool animating_transform_to_screen) {
  DCHECK(ideal_contents_scale_);
  DCHECK(ideal_page_scale_);
  DCHECK(ideal_device_scale_);
  DCHECK(ideal_source_scale_);
  DCHECK(CanHaveTilings());
  DCHECK(!needs_post_commit_initialization_);

  bool change_target_tiling =
      raster_page_scale_ == 0.f ||
      raster_device_scale_ == 0.f ||
      raster_source_scale_ == 0.f ||
      raster_contents_scale_ == 0.f ||
      low_res_raster_contents_scale_ == 0.f ||
      ShouldAdjustRasterScale(animating_transform_to_screen);

  if (tilings_->num_tilings() == 0) {
    DCHECK(change_target_tiling)
        << "A layer with no tilings shouldn't have valid raster scales";
  }

  // Store the value for the next time ShouldAdjustRasterScale is called.
  raster_source_scale_was_animating_ = animating_transform_to_screen;

  if (!change_target_tiling)
    return;

  if (!layer_tree_impl()->device_viewport_valid_for_tile_management())
    return;

  RecalculateRasterScales(animating_transform_to_screen);

  PictureLayerTiling* high_res = NULL;
  PictureLayerTiling* low_res = NULL;

  PictureLayerTiling* previous_low_res = NULL;
  for (size_t i = 0; i < tilings_->num_tilings(); ++i) {
    PictureLayerTiling* tiling = tilings_->tiling_at(i);
    if (tiling->contents_scale() == raster_contents_scale_)
      high_res = tiling;
    if (tiling->contents_scale() == low_res_raster_contents_scale_)
      low_res = tiling;
    if (tiling->resolution() == LOW_RESOLUTION)
      previous_low_res = tiling;

    // Reset all tilings to non-ideal until the end of this function.
    tiling->set_resolution(NON_IDEAL_RESOLUTION);
  }

  if (!high_res) {
    high_res = AddTiling(raster_contents_scale_);
    if (raster_contents_scale_ == low_res_raster_contents_scale_)
      low_res = high_res;
  }

  // Only create new low res tilings when the transform is static.  This
  // prevents wastefully creating a paired low res tiling for every new high res
  // tiling during a pinch or a CSS animation.
  bool is_pinching = layer_tree_impl()->PinchGestureActive();
  if (ShouldHaveLowResTiling() && !is_pinching &&
      !animating_transform_to_screen &&
      !low_res && low_res != high_res)
    low_res = AddTiling(low_res_raster_contents_scale_);

  // Set low-res if we have one.
  if (!low_res)
    low_res = previous_low_res;
  if (low_res && low_res != high_res)
    low_res->set_resolution(LOW_RESOLUTION);

  // Make sure we always have one high-res (even if high == low).
  high_res->set_resolution(HIGH_RESOLUTION);

  SanityCheckTilingState();
}

bool PictureLayerImpl::ShouldAdjustRasterScale(
    bool animating_transform_to_screen) const {
  // TODO(danakj): Adjust raster source scale closer to ideal source scale at
  // a throttled rate. Possibly make use of invalidation_.IsEmpty() on pending
  // tree. This will allow CSS scale changes to get re-rastered at an
  // appropriate rate.

  if (raster_source_scale_was_animating_ && !animating_transform_to_screen)
    return true;

  if (animating_transform_to_screen &&
      raster_contents_scale_ != ideal_contents_scale_ &&
      ShouldUseGpuRasterization())
    return true;

  bool is_pinching = layer_tree_impl()->PinchGestureActive();
  if (is_pinching && raster_page_scale_) {
    // We change our raster scale when it is:
    // - Higher than ideal (need a lower-res tiling available)
    // - Too far from ideal (need a higher-res tiling available)
    float ratio = ideal_page_scale_ / raster_page_scale_;
    if (raster_page_scale_ > ideal_page_scale_ ||
        ratio > kMaxScaleRatioDuringPinch)
      return true;
  }

  if (!is_pinching) {
    // When not pinching, match the ideal page scale factor.
    if (raster_page_scale_ != ideal_page_scale_)
      return true;
  }

  // Always match the ideal device scale factor.
  if (raster_device_scale_ != ideal_device_scale_)
    return true;

  return false;
}

float PictureLayerImpl::SnappedContentsScale(float scale) {
  // If a tiling exists within the max snapping ratio, snap to its scale.
  float snapped_contents_scale = scale;
  float snapped_ratio = kSnapToExistingTilingRatio;
  for (size_t i = 0; i < tilings_->num_tilings(); ++i) {
    float tiling_contents_scale = tilings_->tiling_at(i)->contents_scale();
    float ratio = PositiveRatio(tiling_contents_scale, scale);
    if (ratio < snapped_ratio) {
      snapped_contents_scale = tiling_contents_scale;
      snapped_ratio = ratio;
    }
  }
  return snapped_contents_scale;
}

void PictureLayerImpl::RecalculateRasterScales(
    bool animating_transform_to_screen) {
  raster_device_scale_ = ideal_device_scale_;
  raster_source_scale_ = ideal_source_scale_;

  bool is_pinching = layer_tree_impl()->PinchGestureActive();
  if (!is_pinching || raster_contents_scale_ == 0.f) {
    // When not pinching or when we have no previous scale, we use ideal scale:
    raster_page_scale_ = ideal_page_scale_;
    raster_contents_scale_ = ideal_contents_scale_;
  } else {
    // See ShouldAdjustRasterScale:
    // - When zooming out, preemptively create new tiling at lower resolution.
    // - When zooming in, approximate ideal using multiple of kMaxScaleRatio.
    bool zooming_out = raster_page_scale_ > ideal_page_scale_;
    float desired_contents_scale =
        zooming_out ? raster_contents_scale_ / kMaxScaleRatioDuringPinch
                    : raster_contents_scale_ * kMaxScaleRatioDuringPinch;
    raster_contents_scale_ = SnappedContentsScale(desired_contents_scale);
    raster_page_scale_ = raster_contents_scale_ / raster_device_scale_;
  }

  raster_contents_scale_ =
      std::max(raster_contents_scale_, MinimumContentsScale());

  // Don't allow animating CSS scales to drop below 1 if we're not
  // re-rasterizing during the animation.
  if (animating_transform_to_screen && !ShouldUseGpuRasterization()) {
    raster_contents_scale_ = std::max(
        raster_contents_scale_, 1.f * ideal_page_scale_ * ideal_device_scale_);
  }

  // If this layer would only create one tile at this content scale,
  // don't create a low res tiling.
  gfx::Size content_bounds =
      gfx::ToCeiledSize(gfx::ScaleSize(bounds(), raster_contents_scale_));
  gfx::Size tile_size = CalculateTileSize(content_bounds);
  if (tile_size.width() >= content_bounds.width() &&
      tile_size.height() >= content_bounds.height()) {
    low_res_raster_contents_scale_ = raster_contents_scale_;
    return;
  }

  float low_res_factor =
      layer_tree_impl()->settings().low_res_contents_scale_factor;
  low_res_raster_contents_scale_ = std::max(
      raster_contents_scale_ * low_res_factor,
      MinimumContentsScale());
}

void PictureLayerImpl::CleanUpTilingsOnActiveLayer(
    std::vector<PictureLayerTiling*> used_tilings) {
  DCHECK(layer_tree_impl()->IsActiveTree());
  if (tilings_->num_tilings() == 0)
    return;

  float min_acceptable_high_res_scale = std::min(
      raster_contents_scale_, ideal_contents_scale_);
  float max_acceptable_high_res_scale = std::max(
      raster_contents_scale_, ideal_contents_scale_);

  PictureLayerImpl* twin = twin_layer_;
  if (twin) {
    min_acceptable_high_res_scale = std::min(
        min_acceptable_high_res_scale,
        std::min(twin->raster_contents_scale_, twin->ideal_contents_scale_));
    max_acceptable_high_res_scale = std::max(
        max_acceptable_high_res_scale,
        std::max(twin->raster_contents_scale_, twin->ideal_contents_scale_));
  }

  std::vector<PictureLayerTiling*> to_remove;
  for (size_t i = 0; i < tilings_->num_tilings(); ++i) {
    PictureLayerTiling* tiling = tilings_->tiling_at(i);

    // Keep multiple high resolution tilings even if not used to help
    // activate earlier at non-ideal resolutions.
    if (tiling->contents_scale() >= min_acceptable_high_res_scale &&
        tiling->contents_scale() <= max_acceptable_high_res_scale)
      continue;

    // Keep low resolution tilings, if the layer should have them.
    if (tiling->resolution() == LOW_RESOLUTION && ShouldHaveLowResTiling())
      continue;

    // Don't remove tilings that are being used (and thus would cause a flash.)
    if (std::find(used_tilings.begin(), used_tilings.end(), tiling) !=
        used_tilings.end())
      continue;

    to_remove.push_back(tiling);
  }

  for (size_t i = 0; i < to_remove.size(); ++i) {
    const PictureLayerTiling* twin_tiling = GetTwinTiling(to_remove[i]);
    // Only remove tilings from the twin layer if they have
    // NON_IDEAL_RESOLUTION.
    if (twin_tiling && twin_tiling->resolution() == NON_IDEAL_RESOLUTION)
      twin->RemoveTiling(to_remove[i]->contents_scale());
    tilings_->Remove(to_remove[i]);
  }
  DCHECK_GT(tilings_->num_tilings(), 0u);

  SanityCheckTilingState();
}

float PictureLayerImpl::MinimumContentsScale() const {
  float setting_min = layer_tree_impl()->settings().minimum_contents_scale;

  // If the contents scale is less than 1 / width (also for height),
  // then it will end up having less than one pixel of content in that
  // dimension.  Bump the minimum contents scale up in this case to prevent
  // this from happening.
  int min_dimension = std::min(bounds().width(), bounds().height());
  if (!min_dimension)
    return setting_min;

  return std::max(1.f / min_dimension, setting_min);
}

void PictureLayerImpl::UpdateLCDTextStatus(bool new_status) {
  // Once this layer is not using lcd text, don't switch back.
  if (!is_using_lcd_text_)
    return;

  if (is_using_lcd_text_ == new_status)
    return;

  is_using_lcd_text_ = new_status;
  tilings_->SetCanUseLCDText(is_using_lcd_text_);
}

void PictureLayerImpl::ResetRasterScale() {
  raster_page_scale_ = 0.f;
  raster_device_scale_ = 0.f;
  raster_source_scale_ = 0.f;
  raster_contents_scale_ = 0.f;
  low_res_raster_contents_scale_ = 0.f;

  // When raster scales aren't valid, don't update tile priorities until
  // this layer has been updated via UpdateDrawProperties.
  should_update_tile_priorities_ = false;
}

bool PictureLayerImpl::CanHaveTilings() const {
  if (!DrawsContent())
    return false;
  if (!pile_->HasRecordings())
    return false;
  return true;
}

bool PictureLayerImpl::CanHaveTilingWithScale(float contents_scale) const {
  if (!CanHaveTilings())
    return false;
  if (contents_scale < MinimumContentsScale())
    return false;
  return true;
}

void PictureLayerImpl::SanityCheckTilingState() const {
#if DCHECK_IS_ON
  if (!CanHaveTilings()) {
    DCHECK_EQ(0u, tilings_->num_tilings());
    return;
  }
  if (tilings_->num_tilings() == 0)
    return;

  // MarkVisibleResourcesAsRequired depends on having exactly 1 high res
  // tiling to mark its tiles as being required for activation.
  DCHECK_EQ(1, tilings_->NumHighResTilings());
#endif
}

void PictureLayerImpl::GetDebugBorderProperties(
    SkColor* color,
    float* width) const {
  *color = DebugColors::TiledContentLayerBorderColor();
  *width = DebugColors::TiledContentLayerBorderWidth(layer_tree_impl());
}

void PictureLayerImpl::AsValueInto(base::DictionaryValue* state) const {
  const_cast<PictureLayerImpl*>(this)->DoPostCommitInitializationIfNeeded();
  LayerImpl::AsValueInto(state);
  state->SetDouble("ideal_contents_scale", ideal_contents_scale_);
  state->SetDouble("geometry_contents_scale", contents_scale_x());
  state->Set("tilings", tilings_->AsValue().release());
  state->Set("pictures", pile_->AsValue().release());
  state->Set("invalidation", invalidation_.AsValue().release());

  scoped_ptr<base::ListValue> coverage_tiles(new base::ListValue);
  for (PictureLayerTilingSet::CoverageIterator iter(tilings_.get(),
                                                    contents_scale_x(),
                                                    gfx::Rect(content_bounds()),
                                                    ideal_contents_scale_);
       iter;
       ++iter) {
    scoped_ptr<base::DictionaryValue> tile_data(new base::DictionaryValue);
    tile_data->Set("geometry_rect",
                   MathUtil::AsValue(iter.geometry_rect()).release());
    if (*iter)
      tile_data->Set("tile", TracedValue::CreateIDRef(*iter).release());

    coverage_tiles->Append(tile_data.release());
  }
  state->Set("coverage_tiles", coverage_tiles.release());
  state->SetBoolean("is_using_lcd_text", is_using_lcd_text_);
  state->SetBoolean("using_gpu_rasterization", ShouldUseGpuRasterization());
}

size_t PictureLayerImpl::GPUMemoryUsageInBytes() const {
  const_cast<PictureLayerImpl*>(this)->DoPostCommitInitializationIfNeeded();
  return tilings_->GPUMemoryUsageInBytes();
}

void PictureLayerImpl::RunMicroBenchmark(MicroBenchmarkImpl* benchmark) {
  benchmark->RunOnLayer(this);
}

WhichTree PictureLayerImpl::GetTree() const {
  return layer_tree_impl()->IsActiveTree() ? ACTIVE_TREE : PENDING_TREE;
}

bool PictureLayerImpl::IsOnActiveOrPendingTree() const {
  return !layer_tree_impl()->IsRecycleTree();
}

PictureLayerImpl::LayerRasterTileIterator::LayerRasterTileIterator()
    : layer_(NULL) {}

PictureLayerImpl::LayerRasterTileIterator::LayerRasterTileIterator(
    PictureLayerImpl* layer,
    bool prioritize_low_res)
    : layer_(layer), current_stage_(0) {
  DCHECK(layer_);
  if (!layer_->tilings_ || !layer_->tilings_->num_tilings())
    return;

  WhichTree tree =
      layer_->layer_tree_impl()->IsActiveTree() ? ACTIVE_TREE : PENDING_TREE;

  // Find high and low res tilings and initialize the iterators.
  for (size_t i = 0; i < layer_->tilings_->num_tilings(); ++i) {
    PictureLayerTiling* tiling = layer_->tilings_->tiling_at(i);
    if (tiling->resolution() == HIGH_RESOLUTION) {
      iterators_[HIGH_RES] =
          PictureLayerTiling::TilingRasterTileIterator(tiling, tree);
    }

    if (tiling->resolution() == LOW_RESOLUTION) {
      iterators_[LOW_RES] =
          PictureLayerTiling::TilingRasterTileIterator(tiling, tree);
    }
  }

  if (prioritize_low_res) {
    stages_[0].iterator_type = LOW_RES;
    stages_[0].tile_type = TilePriority::NOW;

    stages_[1].iterator_type = HIGH_RES;
    stages_[1].tile_type = TilePriority::NOW;
  } else {
    stages_[0].iterator_type = HIGH_RES;
    stages_[0].tile_type = TilePriority::NOW;

    stages_[1].iterator_type = LOW_RES;
    stages_[1].tile_type = TilePriority::NOW;
  }

  stages_[2].iterator_type = HIGH_RES;
  stages_[2].tile_type = TilePriority::SOON;

  stages_[3].iterator_type = HIGH_RES;
  stages_[3].tile_type = TilePriority::EVENTUALLY;

  IteratorType index = stages_[current_stage_].iterator_type;
  TilePriority::PriorityBin tile_type = stages_[current_stage_].tile_type;
  if (!iterators_[index] || iterators_[index].get_type() != tile_type)
    ++(*this);
}

PictureLayerImpl::LayerRasterTileIterator::~LayerRasterTileIterator() {}

PictureLayerImpl::LayerRasterTileIterator::operator bool() const {
  return layer_ && static_cast<size_t>(current_stage_) < arraysize(stages_);
}

PictureLayerImpl::LayerRasterTileIterator&
PictureLayerImpl::LayerRasterTileIterator::
operator++() {
  IteratorType index = stages_[current_stage_].iterator_type;
  TilePriority::PriorityBin tile_type = stages_[current_stage_].tile_type;

  // First advance the iterator.
  if (iterators_[index])
    ++iterators_[index];

  if (iterators_[index] && iterators_[index].get_type() == tile_type)
    return *this;

  // Next, advance the stage.
  int stage_count = arraysize(stages_);
  ++current_stage_;
  while (current_stage_ < stage_count) {
    index = stages_[current_stage_].iterator_type;
    tile_type = stages_[current_stage_].tile_type;

    if (iterators_[index] && iterators_[index].get_type() == tile_type)
      break;
    ++current_stage_;
  }
  return *this;
}

Tile* PictureLayerImpl::LayerRasterTileIterator::operator*() {
  DCHECK(*this);

  IteratorType index = stages_[current_stage_].iterator_type;
  DCHECK(iterators_[index]);
  DCHECK(iterators_[index].get_type() == stages_[current_stage_].tile_type);

  return *iterators_[index];
}

}  // namespace cc
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root/cc/layers/picture_layer_impl.cc

DEFINITIONS
